JPS6234429A - Receiver for optical communication - Google Patents

Abstract

PURPOSE:To previously warn incorrect information transmission by means of outside-of-periphery light, by constituting the titled receiver in such a way that a display is made when it is decided that the intensity of the outside-of- periphery light exceeds a prescribed level. CONSTITUTION:A capacitor C1 is used for cutting off a DC component and an inductance L1 and resistance R1 make photoelectric current produced by a signal component to flow to the direction of the capacitor C1 and another photoelectric current produced by an outside-of-periphery component to flow to the direction of the inductance L1. A comparator CON1 compares the voltage across both ends of the resistance R1 corresponding to the intensity of the outside-of-periphery light with a reference voltage and, when the intensity of the outside-of-periphery light exceeds a prescribed value, outputs a warning signal C. When the warning signal C is outputted, a light emission diode for display is made to light by a display driving circuit.

Description

[Detailed description of the invention] Production 1”! The present invention relates to an optical communication device that uses optical signals for signal transmission, and more particularly to a receiving device thereof.

Lost! ul ( Conventionally, optical communication devices have been known that use a light-receiving element such as a photodiode as a receiving means and receive an optical signal from a transmitter by the light-receiving element to enable information transmission and remote control of other devices. ing.

However, in the receiving device of such an optical communication device, the reception! If the light surrounding the l1tf is strong (as is known, shot noise or pulsed light from fluorescent lights), the photodiode will generate a photocurrent, which may cause the receiver to malfunction and prevent accurate information transmission. There is sex.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a receiving device that can prevent such drawbacks and warn of inaccurate information transmission due to external light surrounding the receiving device.

In order to achieve the above object, the present invention provides an external light measurement method that measures the intensity of external light according to surrounding brightness in an optical communication receiving device that receives optical signals from a remote location. a means for determining whether the intensity of the measured external light is equal to or higher than a predetermined level; and a display means for displaying when the intensity of the external light is determined to be equal to or higher than the predetermined level. It is.

Therefore, according to the present invention, when the light surrounding the receiving device is strong and there is a possibility that accurate information transmission may not be carried out due to the interference of ambient light due to shatter noise or fluorescent lights, the display means provides an indication. Therefore, the user can recognize it in advance at a glance.

(The following is a margin) Dog JLI Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a perspective view showing a camera system that transmits photometric information and controls operations using an optical communication device according to an embodiment of the present invention. In Figure 1, (2) is a camera body with a photographic lens (4) attached, and (6) is an optical communication device electrically and mechanically connected to the camera body (2) as described later. receiver, (8) is a bracket that is electrically and mechanically connected to the camera body (2) on the lower surface of the camera body (2), and (10) is a receiver that is connected to the camera body (2) via the bracket (8). ) is an electronic flash device electrically connected to the

As shown in the front view of FIG. 2, the reception fi (6) includes a light receiving window (101) for receiving an optical signal from the transmitter shown in FIG. A light emitting diode (103) is provided for a voltage drop warning which is turned on when the battery check circuit determines that the power supply voltage is insufficient. Furthermore, a pair of light receiving lenses (104) are provided within the light receiving window (101).
) and a pair of upper and lower light shielding doors (105) that can be opened and closed are arranged separately. The light shielding door (ios) has a pair of protrusions (105a) for manual opening and closing.
is formed. (106) is a reception display window, and when a normal reception operation is performed, a reception display layer light emitting diode (107,) arranged inside the window will blink, indicating that a normal reception operation has been performed. is notified to the scratcher controlling the transmitter. At the rear of the pair of light-receiving lenses (104), light-receiving elements (P D , ) (P D 2) each consisting of a photodiode, which will be described later, are arranged.

Then, the receiving fi (6) has an upper part (6a) and a lower part (6b
) and 7 shoes provided at the bottom (6b))
(108) is attached to the camera body (2) by fitting into the 7 joints of the camera body (2), and in this state it is fixed by the fixed neck (109), the shade 77) (108) After the movable contact pin (110) formed in the camera body (2) is fixed, it comes into contact with α and receives! (6) and the camera body (2) are electrically connected. As a result, the camera body (2) receives exposure data and control data sent from the transmitter via the receiver 1fl (6), and further transmits necessary data from the bracket (8). It is also transmitted to the electronic flash device (10) via the electronic flash device (10).

Reception 1s! The upper part (6a) of (6) can rotate relative to the lower part (6b) around the pongee (X) extending in the vertical direction in FIG. 10B) can be changed.

The exposure data received by the receiver (6) is configured to be transmitted to the camera body (2) via a signal cord (111) connected to the input terminal (2a) of the camera body (2). Alternatively, the exposure data can be transmitted from the movable contact pin (110) and the control data can be transmitted from the signal code (IIL).
The configuration may be such that the information is transmitted to the camera body (2), respectively.

FIG. 3 is a block diagram showing the electric circuit of this embodiment. In Fig. 3, (12) indicates a transmitter of an optical communication device that modulates the digital signal to be transmitted to several tens of KHz and emits it as infrared light, and transmits fi (12).
A meter (M) and a transmitting circuit (12a) are provided inside. Here, the meter (M) is, for example,
As proposed by the applicant in No. 9-17897, the brightness of the subject and the amount of flash light are measured and stored using the incident light method, and an appropriate value is determined from the setting data such as film sensitivity, shutter speed, aperture value, etc. and the photometry results. It calculates the shutter speed and aperture value and outputs them as exposure data.

Then, this exposure data is converted into an infrared light signal by the transmitting circuit (12a) and transmitted, and the received e! ! (6)
A light receiving element (P D , ) (P
D2).

(E) is the power supply battery for receiving fi (6), (SW,)
is the power switch of the receiver (6). Power switch (
When SW, ) is closed, the photodetector (PD, ) (P
D2) receives the infrared light signal from the transmitting efl (12) and outputs a current (, ) according to its intensity. This output current (a) is input to the amplification/detection circuit (14), which amplifies and detects this output current (a) and outputs it as a data signal (b) to the subsequent data reading circuit (14).
6). Furthermore, this amplification detection circuit (14)
Send+l'! The light receiving elements (P D 1) (P D 2) of the receiving fi (6) are independent of the infrared light signal from (12).
A warning signal (c) is output when the steady light component (hereinafter referred to as external light) incident on the light reaches a predetermined value or more in intensity.

For the detailed configuration of this amplification/detection circuit (14), see Section 4.
It is shown in the figure and will be described in detail later.

The data reading circuit (16) is a circuit that reads and checks the data signal (b) from the amplification/detection circuit (14), stores the data in order to transmit it to the camera body (2), and transfers the data. Yes, interface 7 for data transfer
Contains Ace circuit. Then, the data reading circuit (
16) transfers the read exposure data to the camera body (2) via the movable contact pin (110) shown in FIG. Furthermore, the data reading circuit (16) includes an amplification detection circuit (
If the data signal (b) transmitted from 14) is correctly read, it outputs a signal (d) indicating that the signal transmitted by optical communication has been correctly read. From then on,
This signal (d) is called a verify signal.

(18) is a timer circuit, and the power supply switch (SW
+) is closed for a certain period of time, the timer signal (e) that is output is set to H''.
) is a NOR circuit (
NOR, ), and further this NOR circuit (NOR, )
The output signal (g) is input to one input terminal of an AND circuit (AND, ). The output signal (r>) of the oscillator (20) is input to the other input terminal of the AND circuit (AND, ).The output signal (g) of the NOR circuit (NOR7) and the AND circuit (AND, ) output signal (h)
are respectively input to six one-shot circuits (22) and (24). These one-shot circuits (22) (2
4) are each configured to output a pulse with a constant time width in response to the rise of the input signals (g) and (h).

Output signal (i) of both one-shot 5-bit circuits (22) (24)
(j) both pass through an OR circuit (OR1) to a signal (k
) is input to the battery check circuit (26). The battery check circuit (26) checks the power supply voltage Vcc at a timing according to the input signal (k), and if the power supply voltage Vcc is below a predetermined value, it latches it and outputs an output signal (1). Then, the voltage drop warning light emitting diode (BCLED) is turned on. The operation of this battery check will be described in detail later.

The warning signal (e) of the amplification detection circuit (14), the verification signal (d) of the data reading circuit (16), and the timer signal (e) of the timer circuit (18) are each an OR circuit ('o R+). is input. Then, the OR circuit (O
The output of RI) is transmitted to the signal (m) via a delay circuit (28).
is input to the display drive circuit (30), and when one input signal of the OR circuit (OR,) becomes H'', the display drive circuit (30 ) lights up the veri 7 eye display light emitting diode (VLED).In other words, the verification display angle light emitting diode (V L E D ) is
The timer circuit (18) is activated when the intensity of the external light exceeds a predetermined value and when the data is accurately read.
If timer No. 5 (e) is output from , it is turned on by the output signal (n) of the display drive circuit (30). Also, when the output of the OR circuit (OR+) becomes L'', after a certain period of time determined by the delay circuit (28), it goes up to the display drive circuit (30) and the light emitting diode (VLED) for displaying the 7 eyes turns off. be done.

Next, FIG. 4 shows the detailed configuration of the amplification/detection circuit (14) of this embodiment. In FIG. The two photodetectors (PD, ) (PD2) are connected in parallel and the output signal (a) is taken out from the 7 node side.
) has an inductance (L, ) and a resistance (
It can be grounded via the Furthermore, the output signal (a) is input to the amplifier (32) via the capacitor (C3), and the output signal (a) is amplified by the amplifier (32). This amplified signal is input to the detection circuit (34), which detects the signal that has been modulated at several tens of KHz and demodulates it to the original digital signal, which is then sent to the subsequent waveform shaping circuit (36). transmitted to. The waveform shaping circuit (36) shapes the waveform of the input signal to be suitable for the subsequent data reading circuit (16), and outputs it as a data signal (b).

The inductance (Ll) is connected in series with the resistor (R4), and the connection point is the humpator (CON,)
is connected to the non-inverting input terminal of On the other hand, Hunpareta (
A reference power supply (Vrefl) that generates a reference voltage is connected to the inverting input terminal of CONl>. Then, the output of the comparator (CON, ) is the aforementioned warning signal (c).
At the same time, it is also input to the base of the transistor (Tr). The flip-flop of this transistor (Tr) is connected to the detection circuit (34) via a resistor (R1), and the emitter is grounded. Furthermore, the detection circuit (34) is grounded via a resistor (R2).

Here, the transistor (Tri) is used as a switch, and is conductive when the output signal of the comparator (CONI) is H'' and is non-conductive when it is II L l''.

The operation of the amplification/detection circuit having such a configuration will now be explained. *First, when extraneous light unrelated to the transmitted signal enters the light receiving element (PD, ) (PD2), a photocurrent proportional to the intensity of the extraneous light is emitted.

This photocurrent has a direct current component or 60Hz x 2 (
The impedance in the direction of the inductance (L,) is low, and the input impedance in the direction of the capacitor (C,) is a DC component or 60Hz (or 50Hz
Since the low frequency component of Hz)X2 has a high impedance, the photocurrent flows in the direction of the inductance (L, ) and the resistance (R8). And resistance (R1)
A voltage corresponding to the photocurrent is generated across the . This voltage is set as the reference power supply (VreL) by the comparator (CONl).
When the voltage across the resistor (R, ) is lower than the reference voltage, the intensity of the external light component is low (because the charging current generated in the photodetector (PDI) (PD2) is small, The output of the comparator (CON, ) becomes “L”,
The warning signal (c) cannot be generated, therefore, in this case, the transistor (Trl) becomes non-conductive, and the current flowing from the detection circuit (34) to 7- and 7- is kept small by the resistor (R2), and its Detection sensitivity is set high. In other words, the light receiving element (PD, ) (P
When the photocurrent generated in D2) is small, the detection circuit (
The sensitivity of 34) is set high.

In this state, the transmission fi (12> to several tens of KHz
The infrared light signal modulated into the photodetector (PD, ) (PD,
), the light receiving element (P D +) (P D 2
) generates a photocurrent due to the external light component and a photocurrent due to the infrared light signal. However, the inductance (L,) has a high impedance with respect to AC component 1, while the impedance of the capacitor (C,) decreases, so the AC component of the output photocurrent of the photodetector (PD, ) (PD,) That is, the charging current component due to the infrared light signal component is input to the amplifier (32) via the capacitor (C5) and amplified. Then, the DC component, that is, the charging current component due to external light, is cut by the capacitor (C1), so
It flows towards the inductance (Ll) and the resistance (R1). The signal amplified by the amplifier (32) is input to the detection circuit (34) set to high sensitivity as described above and detected, and the waveform is shaped by the waveform shaping circuit (36) to form a data signal ( b) as a data reading circuit (
16).

On the contrary, the light receiving element (PD, > (PD2)) by the peripheral light component
If the output photocurrent component of is large and the voltage across the resistor (R,) is greater than the reference voltage, the comparator (CON,
) becomes H”, a warning signal (C) is issued, and the verification display light emitting diode (LED) lights up, indicating that there is a risk that accurate signal transmission may be interfered with by external light. The user is warned. Furthermore, when the output of the comparator (CON, ) becomes "H", the transistor (Tr, ) becomes conductive, and the detection circuit (34) is connected via the resistor (R1) in addition to the resistor (R2). is grounded, and as the current flowing from the detection circuit (34) to the ground increases, its sensitivity decreases.

This is to remove the well-known effects of shot noise and fluorescent lighting. In other words, the intensity of shot noise is approximately proportional to the square root of the brightness of the external light, and when the external light is strong,
The shot noise mentioned above may be mistaken for a signal component, and the pulsed light from a fluorescent lamp may be mistaken for a signal component, so in order to prevent this, in this embodiment, the extraneous light component is If it is strong, the detection circuit (34)
By lowering the sensitivity of the signal, these noises are prevented from being transmitted as a signal.

Here, in order to prevent the output of the comparator (CON,) from repeating 'H' and 'L' due to the illumination of the AC light source, it is necessary to provide hysteresis to the comparator (C0N,). However, since it is not directly related to the present invention, its explanation will be omitted.

That is, to summarize the functions and operations of each electric element in the circuit shown in Figure 4, first, the capacitor (C1) cuts the DC component, and the inductance (L,) and resistance (R,) are The photocurrent due to the signal component is transferred to a capacitor (C
3), and serves to cause the photocurrent due to the peripheral light component to flow in the direction of the inductance (L, ). Furthermore, the comparator (CON+) has a resistance (according to the intensity of the external light component).
The voltage across R3) is compared with a reference voltage to determine whether the intensity of the peripheral light is greater than or equal to a predetermined value. Here, since the inductance (L, ) has almost no DC resistance value, a load resistor can be connected to the photodetector (PD, ) (PD2) by reducing the resistance value of the resistor (R1). It is possible to improve the load characteristics when used. In other words, it is possible to accurately receive optical signals without the circuit becoming saturated even under high illuminance. however,
If the illuminance becomes too high, noise due to the external light component will be transmitted to the data reading circuit (16) as the data signal (b), so in this embodiment, the comparator (CON', )
The detection sensitivity is controlled according to the determination result to prevent noise from being transmitted to the data reading circuit (16), and to display a display when the external light component is strong.

FIG. 5 is a circuit diagram showing a modification of the amplification/detection circuit shown in FIG. 4. In the configuration shown in FIG. 4, the sensitivity of the detection circuit (34) is switched according to the judgment result of the comparator (CON, ), but in this modification, the sensitivity of the detection circuit (34) is changed depending on the judgment result of the comparator (CON,
The amplification degree of the amplifier (32) is adjusted according to the determination result. Regarding the configuration shown in Figure 5,
To explain the difference, the amplifier (32) has a resistor (R
1) and is grounded via a capacitor (C2). Then, the output of the humpator (CON,) whose non-inverting input/inverting input is opposite to that in Fig. 4 is connected in series to the resistor (R6) connected between the amplifier (32) and the capacitor (C2). A transistor with a left-emitter connection (
It is connected to the base of Tr2). Therefore, the amplifier (
The amplification degree of 32) is determined by the resistance (Rs) (Ri).

In other words, when the outer light component is small and the resulting photocurrent is small, the output of the comparator (CON +) is
Since the transistor (Tr2) is conductive, the amplification degree of the amplifier (32) is determined by both the resistors (R3) and (R6), and is set to a high amplification degree.

If the outer light component is large and the resulting photocurrent is higher than the reference voltage, a comparator (CON +
) goes low and the transistor (Trz) is made non-conductive, so the amplification of the amplifier (32) is determined only by the resistor (R1) and is set to a lower amplification. According to this modification, when the extra-circular light component is strong, by lowering the amplification degree of the amplifier (32), the noise is transferred to the data reading circuit (2) as the data signal (b).
16). In this modification, the output of the comparator (CON) is input to the inverter (IV), and the output of this inverter (IV) is used as the warning signal (c).

Furthermore, FIG. 6 is a circuit diagram showing another modification of the amplification/detection circuit shown in FIG. 4. In this modification, the sensitivity of the detection circuit 34) is switched between three levels and one level depending on the determination result of the comparator (CON). In this modification, inductance (L, ) and resistance (R1
) is connected to the non-inverting input terminal of the second comparator (CON2). A second reference power source (Vrefz) that generates a reference voltage higher than the reference power source (Vref+) is connected to the inverting input terminal. And the output of this comparator (CON 2) is
A resistor (R
It is connected to the base of a transistor (T"3) whose collector and emitter are connected in series to 7).

From this configuration, if the voltage across the resistor (R5) corresponding to the intensity of the external light component is sufficiently low, the output of both the comparators (CON, ) (CON2) will be L'' when both are 1, and therefore the transistor (Try ) (Try) are both non-conductive, so the sensitivity of the detection circuit (34) is determined by the resistance (R2
) and has the highest sensitivity. When the voltage across the resistor (R3) becomes a little higher than that, the reference voltage of the reference power supply (Vref+) is lower than the reference voltage of the reference power supply (Vrefz), so only the output of the comparator (CON, ) becomes The signal becomes "H", and only the transistor (Tr) becomes conductive, and the resistor (R3) is connected in parallel to the resistor (R2). Therefore, in this case, the sensitivity of the detection circuit (34) is reduced by one step. Furthermore, when the external light component becomes even stronger and the voltage across the resistor (R1) becomes even higher, the outputs of both the comparators (CON+>(CON2) become I(") and both the transistors (Try>(Tri) become conductive, so the resistor (R2) ) in parallel with the resistor (R1)
and a resistor (R7) are connected, and the sensitivity of the detection circuit (34) is further reduced to the second stage. In this way, according to this modification, the sensitivity of the +11 detection circuit (34) can be changed in three stages. In this modification, the output of the controller 91 is used as the warning signal (c).

If it is necessary to change the sensitivity of the detection circuit in four or more stages, the number of resistors, transistors, comparators, and reference power supplies may be increased in the same way. Further, similarly to the modification shown in FIG. 5, it is possible to easily change the amplification degree of the amplifier (32) in three or more stages depending on the intensity of the outer light component.

The Pt47 diagram shows a circuit configuration in which the load characteristic of the photodiode constituting the light receiving element (PD, ) (PD2) may be bright, so that the signal can be read without the circuit becoming saturated. In such a case, the light receiving element (PD, ) (PD, ) and the inductance (Ll)
The amplifier (32
) input terminal is connected. In this case, the output charging current of the photodetector (PD, > (PD2)) is the capacitor (C
, ) removes the DC component and inputs it to the amplifier (32) for amplification, only the signal is detected by the detection circuit (34), and the output waveform is shaped by the waveform shaping circuit (36). However, with such a configuration, it is not possible to display the intensity of the extra-circular light component as described above, to switch the sensitivity of the detection circuit (34), and to switch the amplification degree of the amplification n (325).

FIG. 8 is a circuit diagram showing still another modification of the amplification/detection circuit shown in FIG. 4. In this modification, the output of the humpator (CON, ) is connected to the other input terminal of an OR circuit (IC, ) whose one input terminal is connected to the output of the waveform shaping circuit (36).

With this configuration, when the intensity of the external light component is low, the output of the comparator (CON, ) remains "L", so the waveform shaping circuit (3
The output signal of 6) is output as is and inputted to the data reading circuit (16). On the other hand, when the intensity of the peripheral light component is large, the output of the filter (CON) is "H".
", and the output of the OR circuit (I'C,) remains 1 (" regardless of the output of the waveform shaping circuit (36). In other words,
When the external light component is large, the signal from the waveform shaping circuit (36) is not input to the data reading circuit (16),
It is fixed at "H". With this configuration, the noise due to the external light component will not be transmitted to the data reading circuit (16), and the malfunction of transmitting an erroneous signal as the data signal (b) to the data reading circuit (16) will not occur.

FIG. 9 is a circuit diagram showing another modification in which only the DC component corresponding to the peripheral light component is selected from the photocurrent of the light receiving element (P D ,>(P D2). In order to extract only the DC component of the photocurrent of (P D ,) (P D 2), a resistor (Ra) and a capacitor (
A smoothing circuit consisting of Ca) is used. and,
The time constant of this smoothing circuit is set so that an alternating current component of about 60 Hz from a fluorescent lamp or the like is extracted from the connection point between the resistor (Ra) and the capacitor (Ca).

If the intensity of the external light is determined according to the output of the connection 2α, only the external light component can be extracted with a simple configuration.

Next, the operation of the battery check system shown in FIG. 3 will be explained using the time chart shown in FIG. 10. f
In the pJ10 diagram, (1) shows the operation when the voltage of the power supply battery (E) is sufficient. First, at time t. When the power switch (SW, ) is closed, a timer signal (e
) is emitted. Further, when the power switch (SW, ) is closed, a signal (r) is generated from the oscillator (20). In this case, neither the warning signal (c) of the amplification/detection circuit (14) nor the verify signal (d) of the data reading circuit (16) is emitted, and both outputs remain at "L". Then, the output signal (r) of the oscillation r# (20) causes the output of the OR circuit (OR,) to become "H", and therefore the OR circuit (
The output signal of the delay circuit (28) becomes "H" with a delay of a predetermined time τ after the output of the delay circuit (28) becomes "H". m) drives the display drive circuit (30), and its output signal (
n) becomes H” and the light emitting diode for verify eye display (
VLED') is lit. Here, since the timer signal (e) becomes H'', the NOR circuit (NOR,)
The output signal (g) of the oscillator (20
The output signal (f) of the AND circuit (AND, ) is the output signal (f) of the AND circuit (AND, ).
11) does not appear.

At time, when the timer signal (e) of the timer circuit (18) becomes "L", the output signal (g> of the NOR circuit (NOR) is inverted to "H", and the output signal (g>) of the Funcitat circuit (22) becomes "H".
) a short pulse signal (i) is emitted. This pulse signal (i) is input to the battery check circuit (26) as a signal (k) via an OR circuit (OR2).

Then, the battery check circuit (26) checks the voltage V of the power supply battery (E) at a timing corresponding to this input pulse (k).
Check cc, power supply voltage Vcc power f in Figure 10 Vr
It is determined whether or not the value is greater than or equal to a predetermined value indicated by ers. During this battery check, the delay circuit (
28) The output signal (starvation) takes a time τ from the output of the OR circuit (OR, ). Since the signal is delayed by 40 seconds and is at H''', the verify display light emitting diode (VLED) continues to be lit.

Then, a fixed time J? determined by the timer circuit (18) from time t0? When flT elapses, the timer signal (e) becomes L'', then the NOR circuit (NORl
) is inverted to "H", so the oscillation signal (r) of the oscillator (20) is output from the AND circuit (AND, ).
) is output from the AND circuit (AND, ), and is input to the one-shot circuit (24) as a signal (h). Therefore, the one-shot circuit (24) outputs a short pulse signal (j) every time the signal (h) rises. The period of this pulse signal (j) is synchronized with the oscillation signal of the oscillator (20).

This pulse signal (j) is input to the battery check circuit (26) as a signal (k) through an OR circuit (OR2), and the power supply voltage vcc is checked at a timing corresponding to this pulse signal (k). .

Time T2 and time' from time L2 to t in FIG.
The time T2 from X'l t 4 to t is the transmitter (1
2) shows the state of each signal when an infrared light signal corresponding to the transmission data is transmitted, the signal is amplified and detected by the amplification detection circuit (14), and read by the data reading circuit (16). ing. In this case, the timer signal (e) of the timer circuit (18) remains at "L", and the warning signal (c) from the amplification/detection circuit (14) also remains at "L" because the extra-frequency light component is small.

If the data reading circuit (16) has accurately read the transmitted data, the “■■” slope will be 7 for a certain period of time T2.
An eye signal (d) is emitted. This verify signal (d
), the output of the OR circuit (OR, ) becomes "H" for a certain period of time when T2 is open, and therefore the output from the delay circuit (28) becomes "H" for a period of time τ. After a delay, the 'H' signal (11) is output for time T2. This H' signal (subject) causes the display drive circuit (3
0) is driven, and the signal (b) remains high for a certain period of time T2.
Therefore, the verification display light emitting diode (V
LED) is lit for a time T2. Furthermore, the verify signal (d) of "H" inverts the output signal (g) of the NOR circuit (NOR) to "L", so the AND circuit (AND
, ) becomes L'', the AND circuit (A
The output signal (11) of N D , ) remains "■-". Therefore, the output signal (f) of the oscillator (20) no longer appears in the output signal (h) of the AND circuit (AND). Therefore, while data is being read, both inputs (i) and (j) of the OR circuit (OR2) remain at "L", so no battery check operation is performed during this time.

Then, when the verify signal (d) of the data reading circuit (16) is inverted to L'' at a certain time,
Similar to time t1, a short pulse signal appears in the output signal (i) of the one-shot circuit (22), and the power supply voltage Vcc is checked by the battery check circuit (26) in accordance with the timing of this pulse.

At this time, the delay circuit (28) inverts the Veri7F signal (d) for a time τ. The display drive circuit (30
), the verify display light emitting diode (VLED) is lit.

Next, the operation from time t8 to t7 in diagram f510 will be explained. This is an operation when the intensity of the external light is high. First, when the amplification detection circuit (14) determines that the intensity of the external light is equal to or higher than a predetermined value, it outputs H" as a warning signal (C). As a result, the output of the OR circuit (OR,) becomes I]", Time τ from the rise of the warning signal (c)
. The light emitting diode (VLE) for verify eye display is
In D), the alpha lamp is turned on and the user is warned that the intensity of the ambient light is high.

In this case, the timer signal (
e) is L'', and the verify signal (d) of the data reading circuit (16) is also L''. Therefore, the NOR circuit (NOR
The output signal (g) of I) becomes H'', and the OR circuit (OR2
As the output signal (k) of ), a short pulse is emitted in response to the oscillation signal (') of the oscillator (20).

As a result, the battery check circuit (26) periodically checks the power supply voltage Vcc.

Here, the timing pulse (signal (k,)) for activating the battery check circuit (26) is generated at time L0.
Opening of tl, between t2 and t, and from t to t5
The reason why it is not emitted during the development period and is emitted only at other times is due to the following reasons. First, from time t0 to time t, it is immediately after the power switch (SW, ) is closed. ) is turned on, and during that time the voltage drop warning light emitting diode (BCLED) is not turned on in order to eliminate confusion in the display. Then, from 2 to t, and from t to t
If the battery check is performed during this opening and the power supply voltage Vcc is below the predetermined value Vref,
When the output signal (0) of the battery check circuit (26) is input to the data reading circuit (16), the verify signal (d) is inverted to "H" and used for verification display. Light emitting diode (VLED)
) is turned off and the operation is stopped, so the lighting time of the verification display light emitting diode (VLED) is shortened and it is no longer open T2 for a certain period of time. Therefore, in this embodiment, the battery check operation is not performed during the above three times.

Furthermore, in the receiver of such an optical communication device, the light emitting display must be visible from a distance, and therefore the display light emitting diode is driven with a very large current. Therefore, it is preferable to also light the voltage drop warning light emitting diode (BOLED) while the verify display light emitting diode (VLED) is lighting. From t+, from L2 to 7, and from L4 to t, the structure is such that the noise/intelligence check is not performed.

However, the time. +τ. From t1+τ. , L2+τ. From t, ten τ. , and t4+τ. When the verification display light emitting diode (VLED) is turned on from t to +τ0, the power supply voltage Vcc is considered to be the lowest just before the light emitting diode (VLED) is turned off, so the light emitting diode (VLED) turning off τ. Only songs,
That is, the configuration is such that a battery check is performed at times t3, tl, and t to check whether or not the Iyl source voltage is stably supplied after the voltage.

(2) in the time chart of FIG. 10 is the power supply voltage Vcc.
The operation is shown when Vref falls below the predetermined value Vref. The battery/terry check circuit (26) is ON1L (
oR, , ) according to the output pulse (k) from the power supply voltage V
cc is checked, and if it is determined that the power supply voltage Vcc has become below the predetermined value Vref* at time t, output (1) (,
) to output "I-(" respectively. By this,
The voltage drop warning light emitting diode (BCLED) is turned on to indicate a drop in the power supply voltage, and the operation of the data reading circuit (16) is stopped. and,
The battery check circuit (26) once checks the power supply voltage Vc.
When c becomes equal to or less than the predetermined value Vrefz, the predetermined value V
Even if ref= or more, the output (I) (o) remains "H", and this can be canceled by the power switch (SW, )
This is done by opening up.

Furthermore, (3) in the time chart in Figure @10 shows what happens when the power supply voltage Vcc drops below the predetermined value ■ref+ while the power switch (swi) is closed and the timer circuit (18) is operating. Showing operation. Here, as mentioned above, the timer signal (e) of the timer circuit (18) is F(
During the period from time t to t, the battery check is not performed and the timer signal (e) is L'''.
After that, time t. Only then is the battery check circuit (26) activated, and it is determined that the power supply voltage Vcc is below the predetermined value Vref3, and the voltage drop warning light emitting diode (BCLED) is lit.

Furthermore, at (4) in the time chart, the power battery (E) is exhausted and the power switch (SW, ) is opened at t+.
+i') Before battery voltage E is the limit voltage for circuit operation and light emitting diode drive. This shows the behavior when the value is lower than . In this case, the power switch (SW
Even if I) is closed, both sales light source (VLED) (BC
Since neither LED (LED) lights up, a voltage drop in the power supply battery (E) is immediately indicated. Here, the time chart (
As is clear from comparing 1) and (4), in the normal state of (1), the verification display light emitting diode (VLE) is turned on for a certain period of time T after the power switch (SW, ) is closed.
If D) is not turned on, it is not possible to display a display that is distinct from the case when the battery voltage drops in (4). Therefore, in this embodiment, the verification display light emitting diode (VLED) is turned on for a certain period of time T in the normal state. There is.

In (5) of the time chart, the data reading circuit (16) accurately reads the transmitted data, and thereby the H'' verify signal (d) is output and the verify display light emitting diode (VLED) is lit. While I was there,
The operation is shown when the power supply voltage Vcc becomes equal to or less than the predetermined value Vref. In this case, as described above, the timing pulse (k) for noise check at time t14 when the light emitting diode (VLED) for verify display is turned off causes the noise check circuit (26
) is activated, the power supply voltage Vcc is checked to determine if it has decreased, and a voltage drop warning light emitting diode (BCLED) is lit to warn of a decrease in the power supply voltage.

Next, the internal structure of the receiving fi (6) shown in the MS1 diagram will be explained. First, FIGS. 11(a) and 11(b) are cross sections B in FIG. 1. In Fig. 11(a) and (b), there is a pair of light receiving lenses (104) inside the light receiving window (101).
, a pair of band pass filters (112), and light receiving elements (P D 1) (P D 2) are arranged in order from the outside world. Further, a pair of upper and lower light shielding doors (105) are provided on the outside side of the light receiving lens (104), respectively. Figure 11(a) shows the case where the opening angle of the light shielding hood (105) is set to fire, and Figure 11(b) shows the case where the opening angle of the light shielding hood (105) is set to fire.
When the opening angle of t7-d (1
The relationship between the position of (15) and the incident light toward the element (PDa) in the light receiving element (PD, ) (PD2) is shown.

FIG. 12 is a perspective view showing the structure of the pair of light-shielding hoods (105) and their rotating shafts (113). (6) The head (
Friction washer (114) sandwiched between
It is frictionally held on the rotating shaft (113) by the frictional force of. The light-shielding 7-door (105) is connected to its operating end (105).
5a), the two rotating shafts (113
), and the opening angle can be set continuously and steplessly to the states shown in FIG. 11 (a) and (b).

FIG. 13 is a graph showing the specific sensitivity incidence characteristic of the light receiving element (PD, ) (PD2) with respect to the incident light flux.

In FIG. 13, the curve (A) shows the characteristic when the opening angle of the light-shielding hood (105) is increased as shown in FIG. This shows the characteristics when the angle of the light-shielding door (105) is made small.

The light shielding door (105) is normally used in the state where the opening angle is at its maximum as shown in FIG. 111(a). In this case, the light beam incident within the range of incidence angle α from the optical axis is
It is possible to capture the entire surface of the PDa. In this case, the specific sensitivity characteristic of the light receiving section becomes wide as shown by the curve (A) in Figure @13. On the other hand, when there is an extremely large amount of external light, that is, when the brightness of the background of the transmitter is extremely high, the receiver cannot receive signals normally. In this case, fIS11 diagram (b)
It is effective to reduce the opening angle of the shield (105) as shown in FIG. In this state, only the light beam incident almost parallel to the optical axis can be received by the entire surface of the element chip (PDa), and the light beam with an incident angle of β or more does not reach the element chip (PDa) at all. In this case, the specific sensitivity characteristic of the light receiving section becomes narrow as shown by curve M(B) in FIG. song#! Comparing (A> and curve (B), both lines have almost the same specific sensitivity on the optical axis (θ=0), and the area surrounded by the curve and the horizontal axis is larger in curve (B) than in curve (B). It can be seen that it is a fraction of A). Therefore,
When the external light is strong, the light is shielded to the state shown in Figure 11 (1+) to obtain the specific sensitivity characteristic represented by curve (B) 7-)
' (105) and send it on the optical axis of the receiver ff1fi (6)! If (12) is installed and communication is performed, the transmission (:Hf1
The sensitivity to (12) remains approximately the same as the state shown in FIG. 11(a), and the influence of external light can be reduced to a fraction of that. As a result, it is possible to achieve normal reception, which was not possible in the state shown in FIG. 11(a).

Furthermore, since the two light shielding doors (105) can be adjusted to open and close independently, it is also possible to set the center of the aperture created by the two light shielding doors at a position offset from the optical axis. . Therefore, it is also possible to set the specific sensitivity characteristic as shown by curve (B) in FIG. 13 with the center shifted from the optical axis.

FIGS. 14(a) and 14(b) respectively show cross section A in FIG. 1. In FIG. 14(,)(b), the reception display window (
A light emitting diode (v L ED ) for displaying a 7-eye display is housed inside the IOC (IOC). Figure 14 (,
) shows a reverse trace of the light rays reflected on the external side surface of the reception display window (106) when viewed from a distance on its optical axis. Moreover, FIG. 14(b) shows a reverse trace of the light ray when the reception display window (106) is viewed from a distance shifted by a certain angle from the optical axis. Furthermore, FIG. 15 shows the spectral transmittance characteristics (C) of the reception display window (106) with respect to the wavelength and the verification display light emitting diode (V
The relative intensity characteristics ([)) with respect to the wavelength of light emitted by L ED ) are shown superimposed.

Regarding the reflected light at the outer surface (106a) of the reception display window (10G), as shown in FIGS. 14(a) and (b),
All the light that reaches the eye is transmitted to the pit wall (6c) of the receiver body (6).
). Therefore, the reception display window (1
06), the pit wall (6C) of the receiver body is reflected on its surface (106a). This pit wall portion (6C) is painted black or the like to have a low reflectance. Therefore, with this configuration, direct reflected light from the outside world does not appear reflected on the outer surface (106a) of the reception display window (106), and a surface with low reflectance appears reflected on the reception display window (106). It is possible to keep the brightness of the surface of (1(') 6 ) low. Also, the reception display window (106)
The side surface of the light emitting diode (]06'b) has exactly the same effect as the outer surface (106b). With this configuration, it is possible to reduce the brightness of external light reflected by the reception display window (106) when viewed from the outside, so that when the internal light emitting diode (7 LED) is turned on, the brightness of the external light can be reduced. It is possible to increase the S/N ratio of brightness when viewed from above, making it easier for an observer to confirm blinking.

In addition, as shown by track #X(C) in FIG. 15, the reception display window (106) transmits most of the light emitted by the Veri 7 eye display light emitting diode (VLED) in the visible range. It is made of a material that absorbs light in other bands. Therefore, a majority of the components of the external light that illuminates the chip surface (ct+) and the reflective surface (rp) of the light emitting diode (VLED) are blocked by the reception display window (106). On the other hand, a light emitting diode for verification display (V L E D
Most of the energy emitted from ) can pass through the reception display window (106) and exit to the outside world. Therefore, the spectral transmittance characteristics of this reception display window (10G) also make it possible to increase the S/N ratio of the brightness seen from the outside when the internal light emitting diode for display (VLED) blinks. This makes it easier for observers to confirm blinking.

As described in detail above, according to this embodiment, when the intensity of the external light is strong and there is a possibility that accurate data communication using the signal light cannot be performed, the light emitting diode for the 7-eye display (
As a warning is issued by lighting up the VLED (VLED), the user can take measures such as changing the direction of the receiver (6) to ensure accurate data communication, and prevent malfunctions due to inaccurate information transmission. can be prevented from occurring. Furthermore, when the intensity of the extra-circular light is strong, the sensitivity of the amplification/detection circuit (14) can be lowered to reduce the possibility of malfunction due to the extra-circular light. Furthermore, according to this embodiment, when the power supply voltage is sufficient, the verification display light emitting diode (VL) is turned on for a certain period of time after the power switch (swi) is closed.
ED) is turned on and the power supply voltage has slightly decreased, the verification display light emitting diode (V
LED) and voltage drop warning light emitting diode (B CL
In addition, if the power supply voltage is very low, the two-party photodiode (V L E
Since neither D) (B CLED) is turned on, three types of states can be distinguished and displayed using the two display elements. Furthermore, according to this embodiment,
The amplification/detection circuit (14) can separate the charging current according to the external light component from the charging current according to the signal component, and the above-mentioned display and sensitivity switching can be performed according to the external light component. , accurate optical communication can be performed even in places where the external light component is strong, such as outdoors.

In addition, in this embodiment, a light receiving element (P
Although the configuration is such that the extraneous light component is detected from the output of D , )(P D 2), the present invention is not limited to this, and a light receiving element may be separately provided for extraneous light detection. However, if it is also used as a light receiving element for signal reception as in this embodiment, the configuration can be simplified.

FIG. 16 is a circuit diagram showing a main part of another embodiment of the present invention in which one of the light receiving elements (P D , ) (P D2) consisting of a photodiode is selected and used according to the temperature. In FIG. 16, the voltage (V
cc) are analog switches (SW2) connected in series to the cathodes of the photodetectors (PD, ) (PD2), respectively.
(SW3). The inverting input terminal of the comparator (CON) is connected to a temperature detection circuit (TD) that detects the temperature and outputs the voltage proportional to the detected temperature. On the other hand, the non-inverting input terminal of the comparator (COH2) is connected to a reference power source (Vref, ) that generates a reference voltage with ground as a reference. The output of the comparator (CON, ) is connected to the date of the analog switch (SW2), and is also connected to the date of the analog switch (SW3) via the inverter circuit (IC3).

In addition, the seven nodes of the light receiving elements (P D 1) (P D 2) are connected to the amplification/detection circuit (shown in Fig. 3) as the output signal (a).
14). Here, in FIG. 17, the spectral sensitivity characteristics of the light receiving elements (P D ,') (P D , ) are shown as curves (KHF>), respectively.

Next, the operation of this embodiment will be explained. First of all, 尤(＋
In a device that performs remote communication 3 using No. 4, it is best to match the spectral sensitivity of the light-receiving element on the receiver side and the spectral sensitivity of the light-emitting diode on the transmitter side. As shown in FIG. 18, the emission peak wavelength shifts from CG) to (H)(I) toward longer wavelengths as the temperature rises.

Therefore, at low temperature, the photodetector 7-(P D , )(PD 2)
Even if the spectral sensitivities of the light-emitting diode and the light-emitting diode are the same, the spectral sensitivity of the light-emitting diode changes as the temperature rises.
Among the charging currents generated by D2), those due to signals become small, and only a large charging current due to external light is generated, resulting in a poor S/N ratio. Therefore, in this embodiment, two photodetectors (PD, > (PD2)) having different spectral sensitivities as shown in Fig. 17 are provided, and the output of the photodetector (PD, ) is used at low temperatures, and when the temperature rises, By configuring the device to use the output of the light receiving element (P D 2), it is possible to operate with a high S/N ratio at both low and high temperatures.

Here, the temperature detection circuit (TD) used in this example
is configured to detect temperature and output a voltage proportional to the temperature. That is, when the temperature is low, the voltage output by the temperature detection circuit (TD) is small, and when the temperature is high, the voltage output is large. Therefore, when the output voltage from the temperature detection circuit (TD) is lower than the voltage from the reference power supply (Vref4), that is, when the temperature is low, the output of the comparator (CON) becomes H''. When the signal enters the date of the analog switch (SW2), the analog switch (SW2) becomes conductive, and the curve (K) of ffN'''
The spectral sensitivity characteristics shown in
) is adopted. At this time, the output of the inverter circuit (IC,) becomes L'', so the analog switch (SW3) is in a non-conducting state.

And as the temperature rises, the temperature detection circuit (TD)
The voltage output by
When the voltage becomes higher than the voltage from "n" (when the temperature becomes high), the output of the humpator (CON 3) becomes L". Then, this signal causes the analog switch (SW2
) becomes non-conductive, while the inverter circuit (IC,
) output becomes “11”, so the analog switch (SW
3) When an H” signal is input to the date, the analog switch (SW, ) becomes conductive, and the output of the photodetector (PD2) is adopted instead of the output of the photodetector (PD, ). .

In this way, two receivers and optical elements with different spectral sensitivities (
At low temperatures, the output of a photodetector (PD, ) having a spectral sensitivity similar to that of a light-emitting diode at low temperatures is adopted, and at high temperatures, By adopting the output of the photodetector (PD2), which has a spectral sensitivity similar to the emission characteristics, the spectral characteristics of the photodetector and light-emitting diode can be matched to each other at low or high temperatures, further improving the S/N ratio. It comes off by letting it go.

Note that the spectral sensitivity characteristics of the light receiving element (P D , ) (P D 2) only need to be similar to the spectral characteristics of the light emitting diode, and do not have to be as shown in FIG. 17.

Furthermore, FIG. 19 is a circuit diagram showing a modification of the embodiment shown in FIG. 16. The modified example shown in tlS19 is provided with three light receiving elements (with three spectral sensitivities), and one of them is adopted according to the temperaturev! It shows precepts. Figure 20 shows
It is a graph showing the spectral sensitivity characteristics of a third light receiving element (PD, ) used in addition to the two light receiving elements (PD, ) (FDP). Note that it is also possible to use four or more light-receiving elements and selectively adopt the output of one of them depending on the temperature, but this configuration can be easily conceived from FIG. I will omit the explanation.

In FIG. 19, the temperature detection circuit (TD) is as shown in FIG. 16, and its output is input to the comparison and selection circuit (CS). Then, the comparison and selection circuit (CS
) is connected to the date of an analog switch (S W z ) connected in series to the photodetector (PDl), and the output (o u T 2) is connected to the photodetector (P
An analog switch (SW 3) connected in series to
) is connected to the date of the analog switch (SW, ), and the output (OUT, ) is connected to the date of the analog switch (SW, ) connected in series to the light receiving element (PD2). Here, the comparison selection circuit (CS) receives a voltage proportional to the temperature from the temperature detection circuit (TD), and when the voltage is small, that is, when the temperature is low, only the output signal (OUT, ) is output. (”
Make it. At this time, the output (OUT 2) and (OU
Both signals of the output (OUT2) are set to ``[]'' when the temperature rises a little and the input voltage of the comparison and selection circuit (CS) increases. OtJT, ) and I/('0UT3) are both "L".Furthermore, when the temperature rises and the input voltage of the comparison and selection circuit (C8) further increases, the comparison and selection circuit (C8)
S) sets only output (OUT,) No. 13 to "H".

Next, the operation of this modified example will be explained. Here, the details of the operation will be understood from the explanation of the embodiment shown in FIG. 11516, and will be briefly described here. When the temperature detected by the temperature detection circuit (TD) is low, only the signal of the output (OUT'T,) of the comparison and selection circuit (CS) becomes l('', which causes the analog switch (SJ) to
Only the light receiving element (PD) is made conductive, and the output of the photodetector (PD) is adopted. When the temperature rises to a point where the S/N ratio is better when using the output of the photodetector (PD,) than when using the output of the photodetector T-(PD,), the comparison and selection circuit (CS) sets only the output (OUT2) to H”,
The output of the photodetector (PD) is used. Furthermore, as the temperature rises, the light receiving element (PD2) becomes more sensitive than the light receiving element (PDt).
When the temperature at which the S/N ratio improves, the comparison and selection circuit (CS) sets only the output (OIJ T ) to "H" and adopts the output of the light receiving element (PD2).

By using a plurality of light-receiving elements having different spectral sensitivities in this way, the S/R ratio can be further improved than in the embodiment shown in FIG.
The N ratio can be improved.

In addition, here, the light receiving element (P D ,) (P D 2) (P
The spectral sensitivity characteristics of D;) do not have to be as shown in FIG.

As described in detail above, the present invention provides an external light measurement method that measures the intensity of external light according to the surrounding brightness in an optical communication receiver that receives optical signals from a remote location. a means for determining whether the intensity of the measured external light is equal to or higher than a predetermined level; and a display means for displaying when the intensity of the external light is determined to be equal to or higher than the predetermined level. With this configuration, if there is a possibility that accurate information transmission may not be carried out due to external light, it is possible to display a message and warn of inaccurate information transmission due to external light surrounding the receiving device. can.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a camera system using an optical communication receiver according to an embodiment of the present invention, FIG. 12 is a front view of the receiver, FIG. 3 is a block diagram showing the electric circuit of the system, and FIG. is a circuit diagram showing the specific configuration of the amplification/detection circuit, FIGS. 5 to FA9 are circuit diagrams showing modified examples of the amplification/detection circuit, and FIG. 10 is a time chart showing the operation of the system in FIG. 3. , FIG. 11 is a cross-sectional view of B in FIG. 1, FIG. 1@12 is a perspective view showing the structure of the light-shielding hood, and FIG. 13 is a graph showing changes in the specific sensitivity of the light-receiving element due to opening and closing of the shielding hood. , Figure 14 is A of Figure 1.
15 is a graph showing the spectral transmittance characteristics of the reception display window and the light emitting characteristics of the light emitting diode, FIG. 16 is a circuit diagram showing the main part of another embodiment, and ff117 is the spectral sensitivity of the light receiving element. Graph showing the characteristics, Figure 18 is a graph showing changes in the light emitting characteristics of the light emitting diode due to temperature, Figure 19 is a circuit diagram showing a modification of Figure 16, and Figure 20 is a graph showing the spectral sensitivity characteristics of the light receiving element. It is. (6); Receiving device for optical communication, (PD,)(PD2)(L,)(R,>(C,
); External light measuring means (CON 1) (CON 2): Judgment means, (V L
ED): Display means. Applicant Minolta Camera Co., Ltd. Figure 1 Figure 7 e c Figure 3, l; +l/rjJ+ Figure 1θ Figure θ) (2) 6 completed)
and f No. 1J Fig. @2 Fig. '4 (b) →Kashi L44ITPL) Fig. q

Claims (1)

[Claims] 1. An optical communication receiving device that receives an optical signal from a remote location, comprising: an external light measuring means for measuring the intensity of external light according to surrounding brightness; 1. A receiving device for optical communication, comprising: a determining means for determining whether the intensity of the external light is equal to or higher than a predetermined level; and a display means for displaying when the intensity of the external light is determined to be equal to or higher than the predetermined level. 2. The receiving device for optical communication according to claim 1, wherein the external light measuring means is also used as a receiving means for receiving an optical signal.